Participation of prostaglandins in the effect of stevioside on rat renal function and arterial pressure

RESUMO

1. The effect if stevuisude ib renal function was evaluated by clearance tecniques in Wistar rats simultaneously with the effect of indomethacin on the renal action of stevioside. The indomethacin experiments consisted of four consectuve periods (C) control; (S), in which stevioside (16 mg/Kg) was continously infused; (S+I1) and (S+I2) in which indomethacin was infused systemically without interrupting stevioside infusion. Mean arterial pressure (MAP) and renal function perameters were measured. 2. Administration of stevioside resulted in a statistically significant dose-related decrease in MAP (121 ñ 2.30, N = 7 for 4mg/Kg stevioside to 72 ñ 4.79 mmHg, N = 7 for 16 mg/Kg stevioside) and an increase in renal plasma flow (RPF) (10.27 ñ 1.21, N = 7 for 4 mg/Kg stevioside to 26.28 ñ 2.87 ml min-1 Kg-1, N = 7 for 16 mg/Kg stevioside), with no change in glomerular filtration rate (GFR). Stevioside also increased fractional sodium (FeNa+) and potassium (FeK+) excretion as well as urine flow (V/GFR). 3. The decrease in MAP (control, 121 ñ 0.93, N = 7; stevioside, 91 ñ 2.48 mmHg) and increase in RPF (control, 14.21 ñ 1.41, N = 7; stevioside, 32.53 ñ 2.84 mmHg) induced by stevioside (16 mg/Kg) were inhibited by simultaneous administration of indomethacin (2 mg/Kg) but GFR was not affected. The diuretic, natriuretic and kaliuretic effects of stevioside were also abolished by indomethacin. 4. We conclud that stevioside behaves like a typical vasodilator substance, causing changes in MAP, diuresis, natriuresis and kaliuresis per ml of GFR, and these effects probably depend on prostaglandins